<!doctype html>
<html lang="zh">

<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
	<meta http-equiv="X-UA-Compatible" content="ie=edge">
	<title>canvas画布实现圆形</title>
</head>

<body>
	<canvas id="myCanvas"   width="300px"   height="300px"></canvas>

</body>

<script>
	var canvas = document.getElementById('myCanvas');
    var   cts=  canvas.getContext("2d");
    cts.fillStyle="red";
    cts.beginPath();
    cts.arc(75,75,50,0,Math.PI*2,true);
    cts.stroke();

</script>

</html>